The difference between a declaration and an affidavit comes down to one procedural step: an affidavit is sworn in front of a notary public who verifies your identity and administers an oath, while a declaration is a written statement you sign yourself “under penalty of perjury” with no notary involved. Under federal law, the two documents carry the same legal weight in most situations, but certain proceedings still require the notarized version, and state rules vary.
How an Affidavit Works
An affidavit is a written statement of facts signed under oath in front of a notary public or other authorized official. The person making the statement (the “affiant”) appears before the notary, swears or affirms that the contents are true, and signs while the notary watches. The notary then administers the oath, signs, and applies an official seal.
The notary is not checking whether your facts are accurate. The notary confirms your identity, usually through a government-issued photo ID, and that you took the oath voluntarily. That identity verification is the main safeguard the affidavit adds over a declaration. If someone later challenges whether you actually signed the document, the notary’s seal and journal entry serve as independent proof.
How a Declaration Works
A declaration skips the notary. You write your statement, add a specific line at the bottom confirming you’re telling the truth “under penalty of perjury,” then sign and date it. The perjury statement is what gives the document its legal weight.
Under federal law, a declaration signed under penalty of perjury carries the same force and effect as a notarized affidavit. The governing statute is 28 U.S.C. § 1746, which requires language substantially like: “I declare under penalty of perjury that the foregoing is true and correct,” followed by the date and your signature.1Office of the Law Revision Counsel. 28 USC 1746 – Unsworn Declarations Under Penalty of Perjury If you sign outside the United States, the statement must also include the phrase “under the laws of the United States of America.”
The wording matters. A declaration that says “I promise this is true” or “I swear this is accurate” may not satisfy the statute. Courts have rejected declarations that don’t track the required language closely enough, so copying the statutory phrase is the safest approach.
Where a Declaration Cannot Replace an Affidavit
Federal law carves out three situations where a declaration under penalty of perjury will not substitute for a sworn, notarized document. You still need a formal oath for depositions, oaths of office, and any oath that a statute specifically requires you to take before a designated official other than a notary public.1Office of the Law Revision Counsel. 28 USC 1746 – Unsworn Declarations Under Penalty of Perjury Outside those exceptions, declarations work anywhere federal law calls for a sworn written statement.
This is where people trip up. Assuming a declaration works everywhere because it works in most federal situations can get your filing rejected. Check the specific rule or statute governing your proceeding before deciding which format to use.
Which One Your Court Will Accept
In federal court, declarations are the default for most written filings. Motions, responses, and supporting factual statements routinely use declarations rather than affidavits, thanks to 28 U.S.C. § 1746.1Office of the Law Revision Counsel. 28 USC 1746 – Unsworn Declarations Under Penalty of Perjury Many attorneys default to declarations in federal practice because they’re faster and don’t require coordinating a notary appointment.
State courts vary. Some states have adopted their own versions of the Uniform Unsworn Declarations Act, which mirrors the federal approach and lets declarations stand in for affidavits in most state proceedings. Many states still require notarized affidavits for specific matters, particularly real estate transactions, probate filings, and certain family law cases. Confirm with the specific court or agency handling your matter before assuming either format will be accepted.
Immigration Filings
Immigration is a common context where this comes up. USCIS accepts affidavits as supporting evidence when primary documents like birth certificates are unavailable. The agency requires at least two affidavits from people with direct personal knowledge of the facts, and each should include the affiant’s full name, contact information, relationship to the applicant, and an explanation of how they know the relevant facts.2USCIS. Chapter 4 – Documentation Because immigration is federal, declarations under penalty of perjury can generally satisfy these requirements, though many immigration attorneys still recommend notarized affidavits because they tend to carry more persuasive weight with the officer reviewing the file.
Cost and Convenience
Declarations cost nothing and can be completed anywhere you have a pen and paper. No notary, no appointment, no ID check. For someone facing a filing deadline, that flexibility can be the difference between submitting on time and missing the window.
Affidavits require more coordination. You need a notary, acceptable photo ID, and in most states a small fee. Notary fees are typically modest, with most states capping them between a few dollars and $25 per signature, though remote online notarizations sometimes carry higher fees. Banks, shipping stores, and law offices often have notaries on staff, but availability outside business hours can be limited.
None of this makes declarations objectively better. When a court or agency specifically requires an affidavit, a declaration will be rejected no matter how convenient it was to prepare. The practical advantages only matter when you have a genuine choice.
Perjury Consequences Are Identical
The federal perjury statute treats lies in affidavits and lies in declarations as the same crime. Section 1621 of Title 18 covers both: subsection (1) addresses false statements made under oath, and subsection (2) addresses false statements in declarations signed under penalty of perjury as permitted by 28 U.S.C. § 1746.3Office of the Law Revision Counsel. 18 USC 1621 – Perjury Generally The penalty is the same either way: a fine, up to five years in federal prison, or both.
A perjury conviction requires that you knowingly stated something false about a fact that matters to the case. Honest mistakes don’t qualify, and neither do lies about irrelevant details. Deliberately misrepresenting a material fact in either document exposes you to the same criminal liability, regardless of whether a notary watched you sign. The perjury statement on a declaration is not a formality. It is the mechanism that puts your freedom on the line, just as effectively as an oath sworn in front of a notary.